Scumbling the lighter colors over previous layers did the trick: the surface of the painting now has some fluid brush work, that flows evenly enough to describe the form. I like the way the yellows at the upper edge of the shadow appear translucent while the lower color is opaque. This effect echoes the way the original object would catch the light. I managed to get a sense of volume; the center of the form illusionistically curves toward us, so the yellow curve is not only a side-to-side movement.
The image in this painting is rather odd in it's massive simplicity. When I work on paintings, there are those that I love throughout the making of them, and others that I feel uncertain about. This painting, with its strange composition and aggressive form, is one of the latter. I'll have to live with it for a while; I'll grow to love it or not. What do you think?
Update: I want to be clear that for me these doubts about my work are a good thing; questioning negates complacency, and can lead to growth and change.